BERLIN, GERMANY - MAY 19: An Opel Ampera electric car, made by General Motors, is plugged in at the Challenge Bibendum fuel efficient cars show at Tempelhof on May 19, 2011 in Berlin, Germany. The ... more

BERLIN, GERMANY - MAY 19: An Opel Ampera electric car, made by General Motors, is plugged in at the Challenge Bibendum fuel efficient cars show at Tempelhof on May 19, 2011 in Berlin, Germany. The trade fair highlights fuel efficient, fuel cell, hybrid and electric car technology. (Photo by Sean Gallup/Getty Images) less